A leading disease incurred by women is breast cancer. Breast cancer is the second leading cause of death for women of all ages and the leading cause of death for women aged 25-55. Approximately one in eight women will incur breast cancer in their lifetimes. Approximately 220,000 surgeries are performed annually in the United States with almost 20 percent requiring the complete removal of the breast. The current medical standard for determining breast cancer in women is mammography. For breast cancer detection, other than clinical examination and self-examination, women rely almost exclusively on mammography. It is estimated that more than 30 million mammograms are performed each year in the U.S. alone. When cancer is detected, mammography is so insensitive that typically the average size of the tumor detected is approximately 1.5 cm. At that size, a tumor has probably been growing, undetected, for nearly 8 years on average. In fact, two-thirds of mammographically detected breast cancer is invasive. In addition, mammography is notorious for “false positive” readings, which lead to many unneeded biopsies. However mammography fails to detect up to 20% of breast cancers in women over 50 and up to 40% of breast cancers in younger women. Breast cancer grows slowly but under current techniques such as mammography the average detection is only on cancer growths which have been growing over seven years at which time the growth size of the cancer generally ranges between 1 and 2 cm. Medical researchers have long recognized that nearly all breast cancer originates in the epithelial lining of the mammary duct system. Furthermore, it is well established that, in its early stages, most breast cancer develops very slowly and remains confined to the mammary ducts for up to 7-10 years. If these very early stages of premalignant and malignant disease could be detected and treated while within the mammary duct system, the result would be substantially better treatment outcomes: enhanced survivability, avoidance of chemotherapy and radiation, and breast conservation.
After detection breast cancer is generally treatable in three ways: surgery, radiation and chemotherapy. Surgery and radiation, of course, have risks and disadvantages well known to those skilled in the art. Chemotherapy also can be particularly disadvantageous as, for example, when the drugs involved cause sickness to the patient when they enter the blood stream.
Today's primary treatment of breast cancer is traditional surgery, either mastectomy or lumpectomy with radiation therapy. Surgery is, by definition, invasive and traumatic. Because the exact margins of cancerous growth are difficult to pinpoint, a surgeon may remove more breast tissue than is necessary or not remove enough. Between newly diagnosed breast cancer surgeries and re-excisions, approximately 180,000 lumpectomies are performed each year in the United States.
Mammary Intraductal Ablation (MIA) refers to a procedure in which the lining of the mammary duct is destroyed to control abnormal intraductal pathology that may or may not be related to malignancy. Today, women with positive mammograms, positive biopsies or intraductal atypia (abnormal pathology) often have a choice of watchful waiting, medical therapy, or surgery (lumpectomy and mastectomy). The advancement of new technology and techniques for the treatment of breast disease has not kept pace with other medical areas, particularly in the area of minimally invasive techniques (mammary ductoscopy).
Intraductal ablation is not intended to replace surgery, which is the definitive treatment for most malignant pathology. However, intraductal ablation gives women a choice in their treatment of abnormal intraductal pathology. Women who want permanent relief from the anxiety associated with breast cancer—can choose endoscopic intraductal ablation. Those who are more concerned about preserving the mammary duct or desire an outpatient procedure with minimal morbidity may find that intraductal ablation is the better choice. Women who participate in the decision making process are more likely to be satisfied with their treatment outcome. All women with negative mammograms and abnormal cytology from intraductal assessment in whom neither Tamoxifen nor mastectomy is desired are candidates for intraductal ablation. In addition, those women who have a positive mammogram (micro-calcifications) or biopsy positive DCIS are candidates for MIA.
Physicians must be careful to maintain strict criteria for performing this procedure on women with positive mammograms or intraductal atypia and not on women with advanced stage breast cancer. Intraductal atypia due to systemic disease may be controlled by appropriate therapy of the underlying medical disorder. In most cases, cancerous or pre-cancerous lesions can be treated with intraductal therapies with or without irradiation or chemotherapy.
Benign conditions that can lead to abnormal intraductal assessment include intraductal papilloma, hyperplasia and atypical ductal hyperplasia and these can be removed without requiring invasive surgery. Likewise, hormonal therapies, and pharmaceutical agents (Tamoxifen) may control the growth of intraductal cancerous lesions. Intraductal ablation can be indicated for women who have not responded to medical therapy or choose not to take the agents due to side effects or other personal reasons. All women should have biopsies or intraductal samplings (ravage) that document the presence of atypia or malignant disease before an intraductal ablation is performed. The mammary duct should also be assessed by office ductoscopy to exclude the possibility of intraductal papillomas, which can be treated with a simple resection. In addition, mammary ductoscopy may reveal women who have multi-focal abnormal epithelia tissue and thus may be candidates for more extensive intraductal therapy.
Intraductal techniques are categorized as either “detection” techniques or “ablation” techniques.
The present detection technique utilizes the mammary ductoscope and additional devices, such as a cytology brush or a tissue biopsy tool. The physician looks directly into the mammary ducts while doing cytology or tissue collection.
The destruction of the intraductal epithelia tissue can be performed by various energy delivering devices including cryotherapy, radiofrequency, microwave energy, bipolar radiofrequency energy, high frequency ultrasound, and laser energy. The Food and Drug Administration (FDA) has approved laser, cryo, ultrasound and RF energy for breast tissue ablation but such ablation is not currently being used within the breast ducts.
Attempts have been made to provide an instrument which will allow the taking of tissue samples within small duct areas. A simple double barrel catheter with adjacent lumens is disclosed in U.S. Pat. No. 6,221,622 with one of the lumens being used to irrigate the milk duct of a breast and the other lumen being used to aspirate the fluid which has entered the duct allowing a continuous flow of saline through the duct which hopefully carries enough cells and tissues for a biopsy. Problems in the use of such an instrument include the small size required by the narrow small diameter lumens which can be blocked or limit the flow of fluid back through the aspiration lumen and thus preclude significant tissue collection or cause duct collapse. While the '622 Patent shows a small lumen size, the size problem is magnified when the other existing prior art is attempted to be applied to breast ducts because of the small size and thin cell walls of the mammary ducts.
The ablation of tissue in various other regions of the body has been previously studied. U.S. Pat. No. 5,107,513 describes the general use of three types of lasers. Carbon dioxide (CO2) laser radiation is intensely absorbed by water and thus acts as a surgical knife and vaporizer, its penetration depth in tissue being 0.03 mm. Argon lasers are minimally absorbed by water but intensely absorbed by hemoglobin and penetrate 1 to 2 mm in most tissue. These lasers are especially useful in coagulating bleeding points in small superficial vessels. Neodymium-Yttrium-Aluminum-Garnet (Nd:YAG) lasers are poorly absorbed by both water and hemoglobin. These lasers are able to penetrate large volumes of tissue, blood clots and coagulate large bleeding vessels. A Holmium laser with a 2100 nm wavelength has good cutting capabilities and its coagulating properties are similar to those of the Nd:YAG laser, penetrating to about 0.4 mm for most tissue. Likewise all of the previously noted energy ablation methods have been used surgically on human beings in much larger areas of operation.
Thus, there is a need in the art for new and better micro-cannula/endoscope assemblies and methods for using same that can be used to directly visualize the mammary ducts of a breast where visualization is by means of endoscopic devices, direct visualization (as opposed to creation of photographic images) and offers the additional advantage that the equipment required is comparatively simple to use and is less expensive than the equipment required to create photographic displays from such images. In addition, there is a need in the art for a method of ablating diseased or abnormal tissue which are located during such visualization within the mammary duct.